GASTONIA, N.C. – The mother of a missing North Carolina boy with autism tearfully pleaded Tuesday for anyone to come forward with information that might help find her son.

"I would appreciate it if you were at the park Saturday and saw Maddox, to please, urgently, please, call the tip line, please,"Carrie Ritch said, reading a statement as the search for Maddox Scott Ritch, who is nonverbal, entered its fourth day. "Continue praying for him because I just want my baby home, please. Whatever you can do."

Ritch appeared at a press conference with authorities who urged any potential witnesses to come forward. The FBI also announced a $10,000 reward for information in the case.

The 6-year-old was last seen Saturday in the Rankin Lake Park in Gastonia. Local, state and federal authorities had expanded their search two miles beyond the park's boundaries, city police said. Hundreds of investigators, analysts and others have joined in the search for the boy in about 250 acres of the park area.

Earlier, police pumped prerecorded messages from his parents into the sprawling park in hopes of drawing out the youngster.

"If he's lost in the woods, he'll be able to hear those messages played, and we're hoping that he'll come to the words of his mother and his father," FBI supervisory special agent Jason Kaplan told reporters on Monday.

The park's grounds include trails and paved walking paths, an 80-acre lake, about a dozen picnic shelters and an 18-hole disc golf course, according to city of Gastonia's website.

The expanded search effort includes ground teams with canines and aircraft, including drones. Police are also employing sonar and infrared technologies.

Authorities are draining water from the lake to expose more of the shoreline for examination, and police are contacting businesses around the park to see if they have useful surveillance video, Gastonia police Chief Robert Helton said.

"We want to make sure that we're checking every possible spot to find this child," he said.

Helton said agents and detectives from more than a dozen local, state and federal agencies are conducting interviews and have generated more than 150 leads.

Maddox was last seen with his father and another adult at the park around 1:30 p.m. Saturday, according to CNN affiliate WSOC in Charlotte.

"They were walking around the lake," Gastonia city spokeswoman Rachel Bagley told WSOC. "They got around to the back side of the lake. He started running, according to the parents, and when they started running after him, they lost sight of him, and no one has seen him ever since."

Helton said authorities would like to talk to an unidentified jogger who was in the park at the time, and to a professional photographer who witnesses said was taking photos of other children dressed in Dr. Seuss costumes.

On Sunday, police canceled all activities at the park and closed it to the public until further notice.

Authorities said they are investigating all possibilities into what led to Maddox's disappearance.

"No piece of information is too small. Something you may think is insignificant could be helpful to our case," Helton said Sunday.

Police said Maddox is 4 feet tall and weighs 45 pounds. He has blond hair and blue eyes. Maddox was last seen wearing an orange T-shirt with the words "I am the man," along with black shorts and closed-toe sandals.

Helton said there were a lot of children in the park on the day Maddox disappeared, including other blond-haired boys wearing orange T-shirts.

"We need to know if you saw our blond-haired boy with the orange shirt," Helton said.

Ritch said her son "is my whole world and my reason for living. He's momma's boy."

"Maddox loves the park. He loves Bouncy Balls and he loves his teddy bear," she said.